Contrast enhancement of remotely-sensed images

Environmental remote sensing is the measurement, from a distance, of the spectral features of the Earth's surface and atmosphere by sensor at the satellites or aircraft. These measurements are formed by the digital image of surface. For any particular area that is being imaged it is unlikely that full dynamic range of the sensor will be used. Not much detail can be seen on the image. Contrast between the dark and light areas for small detail is very low. All this problems make it important to have a contrast enhancement technique for image enhancement. In practice there are two cases for image enhancement. The first is processing of images at the frequency domain. The second is processing of images at the spatial domain.